Magenta ink composition

ABSTRACT

Objects of the present invention are to provide a magenta ink composition having good light-fastness and gas resistance, and excellent moisture resistance and clogging resistance, and to provide a magenta ink composition having excellent colorability in addition to these characteristics. The present invention provides a magenta ink composition containing, as colorants, at least one selected from compounds represented by undermentioned formula (1) and salts thereof, and at least one selected from compounds represented by undermentioned formula (2) and salts thereof. Moreover, the present invention also provides a magenta ink composition containing, as colorants, the above and in addition at least one selected from compounds represented by undermentioned formula (3). (Definitions of the symbols in the formulae are as in the claims.)

BACKGROUND

The present invention relates to a magenta ink composition (this termincludes both a dark magenta ink composition and a light magenta inkcomposition) suitable for ink jet recording.

In recent years, an ink jet recording method has attracted attention.The ink jet recording method is a printing method in which printing iscarried out by making small drops of an ink composition fly onto andthus become attached to a recording medium such as paper. This methodhas the distinctive characteristic that high-quality high-resolutionimages can be printed at high speed using a relatively inexpensiveapparatus. Ink jet recording apparatuses using this method have foundwide commercial acceptance due to good print quality, low cost,relatively quiet operation, and ability to form graphics. Among ink jetrecording apparatuses, thermal (bubble jet (registered trademark)) andpiezoelectric drop-on-demand printers have been especially successful onthe market, and have come to be widely used as printers for personalcomputers in offices and households.

These days, formation of color images is carried out by preparing aplurality of color ink compositions and carrying out ink jet recording.In general, color images are formed using ink compositions of threecolors, i.e. a yellow ink composition, a magenta ink composition and acyan ink composition, or in some cases four colors, with a black inkcomposition added. Furthermore, color images may also be formed usingink compositions of six colors, with a light cyan ink composition and alight magenta ink composition added to the above four colors, or sevencolors, with a dark yellow ink composition further added. The inkcompositions used in such formation of color images are each required tohave good colorability themselves, and in addition when a plurality ofthe ink compositions are combined, it is required to able to producegood intermediate colors, printed articles are required not to discoloror fade during subsequent storage, and so on.

Moreover, in recent years, through continual improvements in all ofheads, ink compositions, recording methods and media, ‘photographicimage quality’ printing using color ink jet printers has reached a levelthat stands comparison with ‘silver salt photography’, and the imagequality has reached ‘photograph-equivalent’. On the other hand, withregard to the storability of obtained images, attempts have been made toimprove the characteristics through improving ink compositions andmedia. In particular, with regard to light-fastness, the characteristicshave been improved to a level at which there is no longer a problem interms of practical use (see Japanese Patent Application Laid-open No.2000-290559, Japanese Patent Application Laid-open No. 2001-288392).However, things are still not on a par with silver salt photography.When evaluating light-fastness, it is standard for judgement to becarried out using as an index the fading rate for pure color patterns(optical density around 1.0) for each of yellow, magenta and cyan. Uponjudging the light-fastnesses of ink compositions loaded into printerscurrently sold on the market using this evaluation method, it is oftenthe case that the light-fastness is lowest for the magenta inkcomposition, and hence the magenta ink composition determines thelight-fast lifetime for the ink set as a whole. Improving thelight-fastness of the magenta ink composition would thus lead to animprovement in the light-fastness of photographic images and alengthening of the light-fast lifetime for the ink set as a whole.

Moreover, printed articles produced using ink compositions as describedabove are placed of course indoors and also sometimes outdoors, andhence are exposed to sunlight and various other types of light and alsothe outside air (ozone, nitrogen oxides, sulfur oxides, etc.); inkcompositions having excellent light-fastness and gas resistance are thusbeing developed. The characteristics of light-fastness and gasresistance are greatly influenced by the colorants in the inks, andhence there are calls for the development of magenta ink compositionsthat are excellent in terms of these characteristics, and also moistureresistance.

As colorants having excellent light-fastness and gas resistance out ofthe above characteristics, compounds (azo dyes) described in JapanesePatent Application Laid-open No. 2002-371079, and compounds(anthrapyridone dyes) described in Japanese PatentApplication Laid-openNo. 2002-332419 have been proposed.

Moreover, with an ink set containing a light magenta ink as describedabove, by including two magenta ink compositions of different colordensities, it has become possible to obtain images with no graininess.With regard to such ink sets containing two ink compositions havingdifferent color densities in this way, which are principally forprinting photographic images, in general it is often the case that theink composition having a low color density is used toalleviate/eliminate graininess when forming photographic images.Moreover, when evaluating the light-fastness as described above, apattern having an optical density of around 1.0 is formed with the inkcomposition having a low color density. Improving the light-fastness ofthe light magenta ink composition thus again leads to an improvement inthe light-fastness of photographic images and a lengthening of thelight-fast lifetime for the ink set as a whole. With an ink compositionhaving a low color density, compared with an ink composition having ahigh color density, not such high colorability is required, and henceother characteristics such as the light-fastness become important.

SUMMARY

It is a first object of the present invention to solve the aboveproblems, and provide a magenta ink composition (this term includes botha dark magenta ink composition and a light magenta ink composition)having good light-fastness and gas resistance, and excellent moistureresistance and clogging resistance.

Moreover, it is a second object of the present invention to solve theabove problems, and provide a magenta ink composition having goodlight-fastness and gas resistance, and excellent moisture resistance,colorability and clogging resistance.

The present inventors have discovered that the above problems can besolved by adopting the constitution of 1 below, thus attaining the abovefirst object.

1. A magenta ink composition of the present invention contains, ascolorants, at least one selected from compounds represented byundermentioned formula (1) and salts thereof, and at least one selectedfrom compounds represented by undermentioned formula (2) and saltsthereof.

(In formula (1), A represents a residue of a 5-membered heterocyclicdiazo component A-NH₂; B¹ and B² represent —CR¹═ and —CR²═ respectively,or one thereof represents a nitrogen atom and the other thereofrepresents —CR¹═ or —CR²═; R⁵ and R⁶ each independently represents ahydrogen atom, an aliphatic group, an aromatic group, a heterocyclicgroup, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group,a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or asulfamoyl group, each group being optionally substituted; G, R¹ and R²each independently represents a hydrogen atom, a halogen atom, analiphatic group, an aromatic group, a heterocyclic group, a cyano group,a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, anaryloxycarbonyl group, an acyl group, a hydroxy group, an alkoxy group,an aryloxy group, a silyloxy group, an acyloxy group, a carbamoyloxygroup, a heterocyclic oxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an alkyl group-, aryl group-, or heterocyclicgroup-substituted amino group, an acylamino group, a ureido group, asulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkyl- or aryl-sulfonylamino group, anitro group, an alkyl- or aryl-thio group, an alkyl- or aryl-sulfonylgroup, an alkyl- or aryl-sulfinyl group, a sulfamoyl group, a sulfogroup, or a heterocyclic thio group, each group being optionallysubstituted; and R¹ and R⁵, or R⁵ and R⁶ may be bonded together to forma 5- or 6-membered ring.)

(In formula (2), A′ represents an alkylene group, a phenylenegroup-containing alkylene group, or

(wherein R represents a hydrogen atom or an alkyl group), and Xrepresents NH₂, OH or Cl.)

Moreover, the present inventors have discovered that the above problemscan be solved by adopting the constitution of 2 below, thus attainingthe above second object.

2. A magenta ink composition of the present invention contains, ascolorants, at least one selected from compounds represented byabove-mentioned formulae (1) and salts thereof, at least one selectedfrom compounds represented by above-mentioned formula (2) and saltsthereof, and at least one selected from compounds represented byundermentioned formula (3).

[In formula (3), Y represents a phenyl group or naphthyl groupsubstituted with a C₁ to C₄ alkyl group or alkoxy group, OH, SO₃H orCOOM; B represents H, or the following formula

(here, R²¹ represents H or a C₁ to C₄ alkyl group substituted with OH orCOOH, R²² represents a C₁ to C₄ alkyl group or phenyl group substitutedwith OH, OCH₃, OC₂H₅, SO₃M, or COOM, R²³ represents OH, COOH, or NHR²⁴,and R²⁴ represents a C₁ to C₄ alkyl group substituted with SO₃M orCOOH); and M represents H, Li, Na, K, ammonium, or an organic amine.]

Furthermore, the present invention also provides magenta inkcompositions according to 3 to 19 below, an ink jet recording methodaccording to 20 below, and a recorded article according to 21 below.

3. The magenta ink composition according to 1 or 2 above, wherein thecompounds represented by formula (1) and salts thereof are compoundsrepresented by undermentioned formula (4) and salts thereof.

(In Formula (4), Z¹ represents an electron-withdrawing group having aHammett substituent constant φp value of at least 0.20; Z² represents ahydrogen atom, an aliphatic group, an aromatic group, or a heterocyclicgroup; R¹, R², R⁵ and R⁶ are defined as in the case of formula (1); R³and R⁴ each independently represents a hydrogen atom, an aliphaticgroup, an aromatic group, a heterocyclic group, an acyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, asulfonyl group, or a sulfamoyl group; Q represents a hydrogen atom, analiphatic group, an aromatic group, or a heterocyclic group; and each ofZ¹, Z², R¹ to R⁶, and Q may be further substituted.)

4. The magenta ink composition according to 1 above, containing 0.2 to2.5 wt % in total of the at least one selected from the compoundsrepresented by formula (1) and salts thereof, and 0.4 to 5.0 wt % intotal of the at least one selected from the compounds represented byformula (2) and salts thereof, relative to the total weight of the inkcomposition.

5. The magenta ink composition according to 2 above, containing 0.3 to1.5 wt % in total of the at least one selected from the compoundsrepresented by formula (1) and salts thereof, 2.0 to 5.0 wt % in totalof the at least one selected from the compounds represented by formula(2) and salts thereof, and 0.5 to 1.5 wt % in total of the at least oneselected from the compounds represented by formula (3), relative to thetotal weight of the ink composition.

6. The magenta ink composition according to 1 above, having a totalcolorant solid content of 0.6 to 6.0 wt % relative to the total weightof the ink composition.

7. The magenta ink composition according to 2 above, having a totalcolorant solid content of 3.5 to 5.5 wt % relative to the total weightof the ink composition.

8. The magenta ink composition according to 1 above, wherein the weightratio of the total content of the at least one selected from thecompounds represented by formula (1) and salts thereof to the totalcontent of the at least one selected from the compounds represented byformula (2) and salts thereof is in a range of 3:1 to 1:5.

9. The magenta ink composition according to 1 above, further containingat least one selected from carboxyl group-possessing aromatic compoundsand salts thereof.

10. The magenta ink composition according to 2 above, further containingat least one selected from carboxyl group-possessing aromatic compoundsand salts thereof.

11. The magenta ink composition according to 9 or 10 above, wherein thecarboxyl group-possessing aromatic compounds and salts thereof arearomatic compounds having one carboxyl group and salts thereof.

12. The magenta ink composition according to 9 or 10 above, wherein thecarboxyl group-possessing aromatic compounds and salts thereof arenaphthalene skeleton-possessing compounds and salts thereof.

13. The magenta ink composition according to 12 above, wherein thenaphthalene skeleton-possessing compounds and salts thereof arecompounds having a carboxyl group in the 2 position and salts thereof.

14. The magenta ink composition according to 13 above, wherein thenaphthalene skeleton-possessing compounds having a carboxyl group in the2 position and salts thereof are 2-napthoic acid, 3-hydroxy-2-napthoicacid, 6-hydroxy-2-napthoic acid, 6-methoxy-2-napthoic acid, and saltsthereof.

15. The magenta ink composition according to 9 or 10 above, wherein thesalts of the carboxyl group-possessing aromatic compounds are lithiumsalts.

16. The magenta ink composition according to 9 above, wherein the weightratio of the total content of the at least one selected from thecompounds represented by formula (1) and salts thereof and the at leastone selected from the compounds represented by formula (2) and saltsthereof to the total content of the at least one selected from thecarboxyl group-possessing aromatic compounds and salts thereof is in arange of 5:1 to 1:3.

17. The magenta ink composition according to 10 above, wherein theweight ratio of the total content of the at least one selected from thecompounds represented by formula (1) and salts thereof, the at least oneselected from the compounds represented by formula (2) and salts thereofand the at least one selected from the compounds represented by formula(3) and salts thereof to the total content of the at least one selectedfrom the carboxyl group-possessing aromatic compounds and salts thereofis in a range of 5:1 to 1:3.

18. The magenta ink composition according to 1 or 2 above, wherein themagenta ink composition is used in an ink jet recording method.

19. The magenta ink composition according to 18 above, wherein the inkjet recording method is a recording method using an ink jet head thatforms ink drops through mechanical deformation of electrostrictiveelements.

20. An ink jet recording method, comprising carrying out recording bydischarging drops of an ink composition and attaching the drops to arecording medium, wherein the ink jet recording method uses the magentaink composition according to 1 or 2 above as the ink composition.

21. A recorded article, obtained by recording using the recording methodaccording to 20 above, or using the magenta ink composition according to1 or 2 above.

Note that ‘magenta ink composition’ in the present invention includesboth a dark magenta ink composition and a light magenta ink composition.

According to an ink composition of the present invention and a recordingmethod using the same, the reliability of the clogging resistance, whichis essential for ink jet recording, is high, and moreover there can beprovided a recorded article for which a high degree of bothlight-fastness and gas resistance (ozone resistance) can be realized,and the moisture resistance is also excellent.

Moreover, according to an ink composition of the present invention and arecording method using the same, the colorability of the inkcomposition, and the reliability of the clogging resistance, which isessential for ink jet recording, are high, and moreover there can beprovided a recorded article for which the light-fastness and gasresistance (ozone resistance), and also the moisture resistance areexcellent.

DESCRIPTION OF DRAWINGS EMBODIMENT A

Following is a detailed description of the present invention, showing anembodiment thereof (hereinafter referred to as ‘embodiment A’).

An ink composition of the present embodiment contains at least thefollowing in water, or an aqueous medium comprising water andwater-soluble organic solvents: at least one magenta colorant selectedfrom compounds represented by formula (1) (including salts thereof;mention of this will be omitted hereinafter) and at least one magentacolorant selected from compounds represented by formula (2) (includingsalts thereof; mention of this will be omitted hereinafter); the inkcomposition may also be made to contain additives such as humectants,viscosity regulators and pH regulators as necessary.

Compounds represented by formula (1) and compounds represented byformula (2) both have excellent light-fastness and gas resistance, withthe compounds represented by formula (1) having particularly goodlight-fastness, and the compounds represented by formula (2) havingparticularly good gas resistance. In the present invention, by usingthese together, a magenta ink composition enabling a high degree of bothlight-fastness and gas resistance to be realized can be provided.

Compounds represented by formula (1) used in the ink composition of thepresent invention have an effect of improving the light-fastness and gasresistance, and one such compound may be used alone or a plurality maybe used together.

Following is a description of compounds represented by formula (1) thatcan be used in the present invention.

In general formula 1, A represents the residue of a 5-memberedheterocyclic diazo component A-NH₂. Examples of each hetero atom in the5-membered heterocyclic ring are N, O and S. A nitrogen-containing5-membered heterocyclic ring is preferable, and the heterocyclic ringmay have an aliphatic ring, an aromatic ring or another heterocyclicring fused thereto. Preferable examples of the heterocyclic ring in Aare a pyrazole ring, an imidazole ring, a thiazole ring, an isothiazolering, a thiadiazole ring, a benzothiazole ring, a benzoxazole ring, anda benzisothiazole ring. This heterocyclic group may be furthersubstituted. Out of the above, pyrazole rings, imidazole rings,isothiazole rings, thiadiazole rings and benzothiazole rings asrepresented by undermentioned general formulae (a) to (f) arepreferable.General Formula

R⁷ to R²⁰ in general formula (a) to (f) represent substituents as for G,R¹ and R², described later. Out of the heterocyclic rings represented bygeneral formula (a) to (f), pyrazole rings and isothiazole ringsrepresented by general formulae (a) and (b) are preferable, withpyrazole rings represented by general formula (a) being most preferable.

B¹ and B² represent —CR¹═ and —CR²═ respectively, or one thereofrepresents a nitrogen atom and the other thereof represents —CR¹═ or—CR²═, with it being more preferable that B¹ and B² represent —CR¹═ and—CR²═ respectively.

R⁵ and R⁶ each independently represents a hydrogen atom, an aliphaticgroup, an aromatic group, a heterocyclic group, an acyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, analkyl- or aryl-sulfonyl group, or a sulfamoyl group, each group beingoptionally substituted. Preferable substituents represented by R⁵ or R⁶are a hydrogen atom, aliphatic groups, aromatic groups, heterocyclicgroups, acyl groups, and alkyl- and aryl-sulfonyl groups, with ahydrogen atom, aromatic groups, heterocyclic groups, acyl groups, andalkyl- and aryl-sulfonyl groups being more preferable, and a hydrogenatom, aryl groups and heterocyclic groups being most preferable. Eachsuch group may be further substituted. Note, however, that R⁵ and R⁶ arenot both simultaneously a hydrogen atom.

G, R¹ and R² each independently represents a hydrogen atom, a halogenatom, an aliphatic group, an aromatic group, a heterocyclic group, acyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonylgroup, an aryloxycarbonyl group, an acyl group, a hydroxy group, analkoxy group, an aryloxy group, a silyloxy group, an acyloxy group, acarbamoyloxy group, a heterocyclic oxy group, an alkoxycarbonyloxygroup, an aryloxycarbonyloxy group, an alkyl group-, aryl group-, orheterocyclic group-substituted amino group, an acylamino group, a ureidogroup, a sulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkyl- or aryl-sulfonylamino group, anitro group, an alkyl- or aryl-thio group, a heterocyclic thio group, analkyl- or aryl-sulfonyl group, an alkylsulfinyl group, an arylsulfinylgroup, a sulfamoyl group, or a sulfo group, each group being optionallysubstituted.

Preferable substituents represented by G are a hydrogen atom, halogenatoms, aliphatic groups, aromatic groups, a hydroxy group, alkoxygroups, aryloxy groups, acyloxy groups, heterocyclic oxy groups, alkylgroup-, aryl group-, and heterocyclic group-substituted amino groups,acylamino groups, ureido groups, sulfamoylamino groups,alkoxycarbonylamino groups, aryloxycarbonylamino groups, alkyl- andaryl-thio groups, and heterocyclic thio groups, with a hydrogen atom,halogen atoms, alkyl groups, a hydroxy group, alkoxy groups, aryloxygroups, acyloxy groups, alkyl group-, aryl group-, and heterocyclicgroup-substituted amino groups, and acylamino groups being morepreferable, and out of these a hydrogen atom, arylamino groups and amidegroups being most preferable. Each such group may be furthersubstituted.

Preferable substituents represented by R¹ or R² are a hydrogen atom,alkyl groups, alkoxycarbonyl groups, a carboxyl group, carbamoyl groups,and a cyano group. Each such group may further be further substituted.R¹ and R⁵, or R⁵ and R⁶ may be bonded together to form a 5- or6-membered ring. Examples of substituents in the case that any of thesubstituents represented by A, R¹, R², R⁵, R⁶ and G is furthersubstituted are the substituents listed for G, R¹ and R² above.

In the case that an azo dye represented by formula (1) is awater-soluble dye, the azo dye preferably further has ionic hydrophilicgroups as substituents in any of the positions on A, R¹, R², R⁵, R⁶ orG. Such ionic hydrophilic groups include a sulfo group, a carboxylgroup, and a quaternary ammonium group. As such ionic hydrophilicgroups, a carboxyl group and a sulfo group are preferable, with a sulfogroup being particularly preferable. Such a carboxyl group or sulfogroup may be in the form of a salt, with examples of counter ionsforming the salt being alkali metal ions (e.g. a sodium ion, a potassiumion, or a lithium ion), an ammonium ion, and organic cations (e.g. atetramethylammonium or tetramethylguanidium ion).

Following is a detailed description of the substituents represented byG, R¹ and R².

Examples of halogen atoms are a fluorine atom, a chlorine atom, and abromine atom.

In the present specification, ‘aliphatic groups’ means alkyl groups,substituted alkyl groups, alkenyl groups, substituted alkenyl groups,alkynyl groups, substituted alkynyl groups, aralkyl groups, andsubstituted aralkyl groups. Such an aliphatic group may be branched, ormay form a ring. The number of carbon atoms in the aliphatic group ispreferably 1 to 20, more preferably 1 to 16. The aryl part of an aralkylgroup or substituted aralkyl group is preferably phenyl or naphthyl,particularly preferably phenyl. Examples of aliphatic groups includemethyl, ethyl, butyl, isopropyl, t-butyl, hydroxyethyl, methoxyethyl,cyanoethyl, trifluoromethyl, 3-sulfopropyl, 4-sulfobutyl, a cyclohexylgroup, a benzyl group, a 2-phenethyl group, a vinyl group, and an allylgroup.

In the present specification ‘aromatic groups’ means aryl groups andsubstituted aryl groups. Preferable aryl groups are phenyl and naphthyl,with phenyl being particularly preferable. The number of carbon atoms inthe aromatic group is preferably 6 to 20, more preferably 6 to 16.Examples of aromatic groups include phenyl, p-tolyl, p-methoxyphenyl,o-chlorophenyl, and m-(3-sulfopropylamino)phenyl. ‘Heterocyclic groups’include substituted heterocyclic groups and unsubstituted heterocyclicgroups. The heterocyclic ring may have an aliphatic ring, an aromaticring or another heterocyclic ring fused thereto. The heterocyclic groupis preferably a 5- or 6-membered heterocyclic group. Examples ofsubstituents include aliphatic groups, halogen atoms, alkyl- andaryl-sulfonyl groups, acyl groups, acylamino groups, sulfamoyl groups,carbamoyl groups, and ionic hydrophilic groups. Examples of heterocyclicgroups include a 2-pyridyl group, a 2-thienyl group, a 2-thiazolylgroup, a 2-benzothiazolyl group, a 2-benzoxazolyl group, and a 2-furylgroup.

Carbamoyl groups include substituted carbamoyl groups and anunsubstituted carbamoyl group. Examples of substituents include alkylgroups. Examples of carbamoyl groups include a methylcarbamoyl group anda dimethylcarbamoyl group.

Alkoxycarbonyl groups include substituted alkoxycarbonyl groups andunsubstituted alkoxycarbonyl groups. As an alkoxycarbonyl group, onehaving 2 to 12 carbon atoms is preferable. Examples of substituentsinclude ionic hydrophilic groups. Examples of alkoxycarbonyl groupsinclude a methoxycarbonyl group and an ethoxycarbonyl group.

Aryloxycarbonyl groups include substituted aryloxycarbonyl groups andunsubstituted aryloxycarbonyl groups. As an aryloxycarbonyl group, onehaving 7 to 12 carbon atoms is preferable. Examples of substituentsinclude ionic hydrophilic groups. Examples of aryloxycarbonyl groupsinclude a phenoxycarbonyl group.

Acyl groups include substituted acyl groups and unsubstituted acylgroups. As an acyl group, one having 1 to 12 carbon atoms is preferable.Examples of substituents include ionic hydrophilic groups. Examples ofacyl groups include an acetyl group and a benzoyl group.

Alkoxy groups include substituted alkoxy groups and unsubstituted alkoxygroups. As an alkoxy group, one having 1 to 12 carbon atoms is.preferable. Examples of substituents include alkoxy groups, a hydroxygroup, and ionic hydrophilic groups. Examples of alkoxy groups include amethoxy group, an ethoxy group, an isopropoxy group, a methoxyethoxygroup, a hydroxyethoxy group, and a 3-carboxypropoxy group.

Aryloxy groups include substituted aryloxy groups and unsubstitutedaryloxy groups. As an aryloxy group, one having 6 to 12 carbon atoms ispreferable. Examples of substituents include alkoxy groups and ionichydrophilic groups. Examples of aryloxy groups include a phenoxy group,a p-methoxyphenoxy group, and an o-methoxyphenoxy group.

Acyloxy groups include substituted acyloxy groups and unsubstitutedacyloxy groups. As an acyloxy group, one having 1 to 12 carbon atoms ispreferable. Examples of substituents include ionic hydrophilic groups.Examples of acyloxy groups include an acetoxy group and a benzoyloxygroup.

Carbamoyloxy groups include substituted carbamoyloxy groups and anunsubstituted carbamoyloxy group. Examples of substituents include alkylgroups. Examples of carbamoyloxy groups include an N-methylcarbamoyloxygroup.

An alkyl group-, aryl group-, or heterocyclic group-substituted aminogroup substituent may be further substituted. An unsubstituted aminogroup is not included. As an alkylamino group, one having 1 to 6 carbonatoms is preferable. Examples of substituents include ionic hydrophilicgroups. Examples of alkylamino groups include a methylamino group and adiethylamino group. Arylamino groups include substituted arylaminogroups and unsubstituted arylamino groups. As an arylamino group, onehaving 6 to 12 carbon atoms is preferable. Examples of substituentsinclude halogen atoms and ionic hydrophilic groups. Examples ofarylamino groups include an analino group and a 2-chloroanalino group.

Acylamino groups include substituted acylamino groups. As an acylaminogroup, one having 2 to 12 carbon atoms is preferable. Examples ofsubstituents include ionic hydrophilic groups. Examples of acylaminogroups include an acetylamino group, a propionylamino group, abenzoylamino group, an N-phenylacetylamino group, and a3,5-disulfobenzoylamino group.

Ureido groups include substituted ureido groups and an unsubstitutedureido group. As a ureido group, one having 1 to 12 carbon atoms ispreferable. Examples of substituents include alkyl groups and arylgroups. Examples of ureido groups include a 3-methylureido group, a3,3-dimethylureido group, and a 3-phenylureido group.

Sulfamoylamino groups include substituted sulfamoylamino groups and anunsubstituted sulfamoylamino group. Examples of substituents includealkyl groups. Examples of sulfamoylamino groups include anN,N-dipropylsulfamoylamino group.

Alkoxycarbonylamino groups include substituted alkoxycarbonylaminogroups and unsubstituted alkoxycarbonylamino groups. As analkoxycarbonylamino group, one having 2 to 12 carbon atoms ispreferable. Examples of substituents include ionic hydrophilic groups.Examples of alkoxycarbonylamino groups include an ethoxycarbonylaminogroup.

Aryloxycarbonylamino groups include substituted aryloxycarbonylaminogroups and unsubstituted aryloxycarbonylamino groups. As anaryloxycarbonylamino group, one having 7 to 12 carbon atoms ispreferable. Examples of substituents include ionic hydrophilic groups.Examples of aryloxycarbonylamino groups include a phenoxycarbonylaminogroup.

Alkyl- and aryl-sulfonylamino groups include substituted alkyl- andaryl-sulfonylamino groups and unsubstituted alkyl- andaryl-sulfonylamino groups. As a sulfonylamino group, one having 1 to 12carbon atoms is preferable. Examples of substituents include ionichydrophilic groups. Examples of sulfonylamino groups include amethanesulfonylamino group, an N-phenylmethanesulfonylamino group, abenzenesulfonylamino group, and a 3-carboxybenzenesulfonylamino group.

Alkyl-, aryl- and heterocyclic thio groups include substituted alkyl-,aryl- and heterocyclic thio groups and unsubstituted alkyl-, aryl- andheterocyclic thio groups. As an alkyl-, aryl- or heterocyclic thiogroup, one having 1 to-12 carbon atoms is preferable. Examples ofsubstituents include ionic hydrophilic groups. Examples of alkyl-, aryl-and heterocyclic thio groups include a methylthio group, a phenylthiogroup, and a 2-pyridylthio group.

Examples of alkyl- and aryl-sulfonyl groups include a methanesulfonylgroup and a phenylsulfonyl group respectively. Examples of alkyl- andaryl-sulfinyl groups include a methanesulfinyl group and aphenylsulfinyl group respectively.

Sulfamoyl groups include substituted sulfamoyl groups and anunsubstituted sulfamoyl group. Examples of substituents include alkylgroups. Examples of sulfamoyl groups include a dimethylsulfamoyl groupand a di-(2-hydroxyethyl)sulfamoyl group.

In the present invention, particularly preferable azo dyes are onesrepresented by formula (4). In the formula, Z¹ represents anelectron-withdrawing group having a Hammett substituent constant upvalue of at least 0.20. Z¹ is preferably an electron-withdrawing grouphaving a up value of 0.30 to 1.0. Specific examples of preferablesubstituents are the electron-withdrawing substituents mentioned later,but of these, acyl groups having 2 to 12 carbon atoms, alkyloxycarbonylgroups having 2 to 12 carbon atoms, a nitro group, a cyano group,alkylsulfonyl groups having 1 to 12 carbon atoms, arylsulfonyl groupshaving 6 to 18 carbon atoms, carbamoyl groups having 1 to 12 carbonatoms, and halogenated alkyl groups having 1 to 12 carbon atoms arepreferable. Acyano group, alkylsulfonyl groups having 1 to 12 carbonatoms, and arylsulfonyl groups having 6 to 18 carbon atoms areparticularly preferable, with a cyano group being most preferable.

R¹, R², R⁵ and R⁶ are defined as in the case of formula (1). R³ and R⁴each independently represents a hydrogen atom, an aliphatic group, anaromatic group, a heterocyclic group, an acyl group, an alkoxycarbonylgroup, an aryloxycarbonyl group, a carbamoyl group, an alkyl- oraryl-sulfonyl group, or a sulfamoyl group. Of these, a hydrogen atom,aromatic groups, heterocyclic groups, acyl groups, and alkyl- andaryl-sulfonyl groups are preferable, with a hydrogen atom, aromaticgroups and heterocyclic groups being particularly preferable. Z²represents a hydrogen atom, an aliphatic group, an aromatic group, or aheterocyclic group.

Q represent a hydrogen atom, an aliphatic group, an aromatic group, or aheterocyclic group. Of these, Q is preferably a group comprising a setof non-metallic atoms required to form a 5- to 8-membered ring. This 5-to 8-membered ring may be substituted, and may be a saturated ring ormay have unsaturated bonds. Of such groups, aromatic groups andheterocyclic groups are particularly preferable. Preferable non-metallicatoms are nitrogen atoms, oxygen atoms, sulfur atoms and carbon atoms.Specific examples of the 5- to 8-membered ring include a benzene ring, acyclopentane ring, a cyclohexane ring, a cycloheptane ring, acyclooctane ring, a cyclohexene ring, a pyridine ring, a pyrimidinering, a pyrazine ring, a pyridazine ring, a triazine ring, an imidazolering, a benzimidazole ring, an oxazole ring, a benzoxazole ring, athiazole ring, a benzothiazole ring, an oxane ring, a sulfolane ring,and a thiane ring.

Each group described for formula (4) may be further substituted. In thecase that these groups are further substituted, examples of thesubstituents are the groups given as examples for substituents, G, R¹and R² for formula (1), and ionic hydrophilic groups.

Here, regarding the substituent Z¹, a description will now be given ofthe Hammett substituent constant φp value used in the presentspecification. Hammelt's rule is an empirical rule proposed by L. P.Hammett in 1935 for quantitatively discussing the effects ofsubstituents on the reactions or equilibrium of benzene derivatives, andis accepted as having wide validity even today. As substituent constantsdetermined according to Hammett's rule, there are the σp value and theσm value, and these values can be found in many general compendia, withfor example ‘Lange's Handbook of Chemistry’, 12^(th) edition, 1979,edited by J. A. Dean (McGraw-Hill) and ‘Kagaku no Ryoiki’, specialissue, no. 122, pages 96 to 103, 1979 (Nankodo) being detailed. Notethat in the present invention, the substituent is limited and describedthrough the Hammett substituent constant σp, but it goes without sayingthat this does not mean that the substituent is limited to only onesthat can be found in the above compendia, i.e. ones for which there is aknown literature value, but rather substituents for which the value maynot be known from the literature but would presumably fall within theabove range if measured based on Hammett's rule are also included.Moreover, in formulae (1) and (5) in the present invention, compoundsother than benzene derivatives are included, but the σp value is stillused as an indicator of the electronic effect of the substituentregardless of the substitution site. In the present invention, ‘σpvalue’ is used with such a meaning.

Examples of electron-withdrawing groups having a Hammett substituentconstant up value of at least 0.60 include a cyano group, a nitro group,alkylsulfonyl groups (e.g. a methanesulfonyl group), and arylsulfonylgroups (e.g. a benzenesulfonyl group). Examples of electron-withdrawinggroups having a Hammett up value of at least 0.45 include, in additionto the above, acyl groups (e.g. an acetyl group), alkoxycarbonyl groups(e.g. a dodecyloxycarbonyl group), aryloxycarbonyl groups (e.g.m-chlorophenoxycarbonyl), alkylsulfinyl groups (e.g. n-propylsulfinyl),arylsulfinyl groups (e.g. phenylsulfinyl), sulfamoyl groups (e.g.N-ethylsulfamoyl, N,N-dimethylsulfamoyl), and halogenated alkyl groups(e.g. trifluoromethyl).

Examples of electron-withdrawing groups having a Hammett substituentconstant σp value of at least 0.30 include, in addition to the above,acyloxy groups (e.g. acetoxy), carbamoyl groups (e.g. N-ethylcarbamoyl,N,N-dibutylcarbamoyl), halogenated alkoxy groups (e.g.trifluoromethyloxy), halogenated aryloxy groups (e.g.pentafluorophenyloxy), sulfonyloxy groups (e.g. a methylsulfonyloxygroup), halogenated alkylthio groups (e.g. difluoromethylthio), arylgroups substituted with at least two electron-withdrawing groups havingan φp value of at least 0.15 (e.g. 2,4-dinitrophenyl,pentachlorophenyl), and heterocyclic rings (e.g. 2-benzoxazolyl,2-benzothiazolyl, 1-phenyl-2-benzimidazolyl). Specific examples ofelectron-withdrawing groups having a φp value of at least 0.20 include,in addition to the above, halogen atoms.

Particularly preferable combinations of substituents in an azo dyerepresented by formula (1) are as follows.

-   -   (i) R⁵ and R⁶ are each preferably a hydrogen atom, an alkyl        group, an aryl group, a heterocyclic group, a sulfonyl group, or        an acyl group, with a hydrogen atom, an aryl group, a        heterocyclic group, or a sulfonyl group being more preferable,        and a hydrogen atom, an aryl group, or a heterocyclic group        being most preferable. Note, however, that R⁵ and R⁶ are not        both simultaneously a hydrogen atom.    -   (ii) G is preferably a hydrogen atom, a halogen atom, an alkyl        group, a hydroxy group, an amino group, or an amide group, with        a hydrogen atom, a halogen atom, an amino group, or an amide        group being more preferable, and a hydrogen atom, an amino        group, or an amide group being most preferable.    -   (iii) A is preferably a pyrazole ring, an imidazole ring, an        isothiazole ring, a thiadiazole ring, or a benzothiazole ring,        with a pyrazole ring or an isothiazole ring being more        preferable, and a pyrazole ring being most preferable.    -   (iv) B¹ and B² are preferably —CR¹═ and —CR²═ respectively, and        R¹ and R² thereof are each preferably a hydrogen atom, a halogen        atom, a cyano group, a carbamoyl group, a carboxyl group, an        alkyl group, a hydroxy group, or an alkoxy group, with a        hydrogen atom, a cyano group, a carbamoyl group, or an alkyl        group being more preferable.

Moreover, regarding preferable combinations of substituents for acompound represented by formula (1), a compound in which at least one ofthe various substituents is a preferable group as listed above ispreferable, a compound in which more of the various substituents arepreferable groups as listed above is more preferable, and a compound inwhich all of the substituents are preferable groups as listed above ismost preferable.

A compound represented by formula (1) may be manufactured using anymethod, but can, for example, be manufactured using a method such as thefollowing.

-   -   (a) A compound represented by undermentioned formula (5) and a        diazotizing agent are reacted together to form a diazonium salt.    -   (b) The diazonium salt formed-in step (a) above is reacted with        a coupling agent represented by undermentioned formula (6), thus        forming a compound represented by formula (1).    -   (c) The compound formed in step (b) above is reacted with an        alkylating agent, an arylating agent or a heterylating agent        under the presence of a base, thus forming a compound        represented by formula (1) having substituents such as alkyl        groups introduced therein.        A-NH₂   Formula (5)        (In the formula, A, G, B¹, B², R⁵ and R⁶ are defined as in the        case of formula (1)).

Furthermore, in the case that water-soluble groups are to be introducedinto the compound of general formula (1), an electrophilic reaction isused. Examples of the electrophilic reaction are a sulfonation reaction,a Mannich reaction, and a Friedel-Crafts reaction, with a sulfonationreaction being preferable out of these.

Following are specific examples of compounds represented by formula (1)that can be preferably used in the present invention. TABLE 1

Dye R₁ R₂ 1

2

3

4

Dye R₃ R₄ 1

2

3

4

TABLE 2

Dye R₁ R₂ R₃ R₄ 5

6

7

TABLE 3

Dye R₁ R₂ R₃ R₄ 8

9

10

11

12

TABLE 4

Dye R₁ R₂ 13

14

15

16

17

Dye R₃ R₄ 13

14

15

16

17

TABLE 5

Dye R₁ R₂ R₃ R₄ R₅ R₆ b-1 CH₃ H CN H

b-2 CH₃ H H SO₂CH₃

TABLE 6

Dye R₁ R₂ R₃ R₄ R₅ R₆ c-1

H CONH₂ H

c-2

CH₃ H

The total content of the at least one compound of formula (1) ispreferably in a range of 0.2 to 2.5 wt %, more preferably 0.3 to 2.0 wt%, relative to the total weight of the ink composition. By making thiscontent be at least 0.2 wt %, the light-fastness and gas resistance canbe improved, and by making this content be not more than 2.5 wt %, adrop in the moisture resistance can be prevented.

Compounds represented by formula (2) used in the ink composition of thepresent invention have an effect of improving the light-fastness and gasresistance, and one such compound may be used alone or a plurality maybe used together.

A compound of formula (2) may be manufactured using any method, but can,for example, be manufactured using a method such as the following.

-   -   1) Benzoylacetic acid ethyl ester is reacted with        1-methylamino4-bromoanthraquinone in a solvent, thus obtaining 1        -benzoyl-6-bromo-2,7-dihydro-3-methyl-2,7-dioxy-3H-dibenz[f,ij]isoquinoline.    -   2) Next, the compound obtained in 1) above and        meta-aminoacetanilide are reacted together in a solvent, thus        obtaining        3′-[1-benzoyl-2,7-dihydro-3-methyl-2,7-dioxo-3H-dibenz[f,ij]isoquinolin-6-ylamino]-ace        tanilide.    -   3) Next, the compound obtained- in 2) above is reacted in fuming        sulfuric acid, thus obtaining        trisodium-6-amino-4-[2,7-dihydro-3-methyl-1-(3-sulfonatobenzoyl)-2,7-dioxo-3H-dibenz[f,ij]isoquinolin-6-ylamino]-benzene-1,3-disulfonate.    -   4) Next, the compound obtained in 3) above and cyanuric chloride        are reacted together in water, thus obtaining a primary        condensation product, and then reaction is further carried out        with a diamine having a connecting group A′, thus obtaining a        secondary condensation product.

5) Next, the compound obtained in 4) above is taken as is, or ishydrolyzed, or is reacted with ammonia to form a tertiary condensationproduct, thus obtaining the target compound represented by formula (2).

The total content of the at least one compound of formula (2) ispreferably in a range of 0.4 to 5.0 wt %, more preferably 1.0 to 4.0 wt%, relative to the total weight of the ink composition. By making thiscontent be at least 0.4 wt %, the light-fastness and gas resistance canbe improved, and by making this content be not more than 5.0 wt %, adrop in the clogging resistance can be prevented.

Moreover, the weight ratio of the total content of the at least onecompound represented by formula (1) to the total content of the at leastone compound represented by formula (2) is preferably in a range of 3:1to 1:5, more preferably 2:1 to 1:4. By making the two compounds becontained in such a ratio, a high degree of both light-fastness andozone resistance can be realized.

Moreover, to adjust the color tone and so on, other magenta dyes canalso be used in the magenta ink composition of the present invention, solong as this is within a range such that the various properties such asthe light-fastness are not greatly damaged.

Examples of magenta dyes other than compounds represented by formula (1)or (2) include C.I. Direct Reds 2, 4, 9, 23, 26, 31, 39, 62, 63, 72, 75,76, 79, 80, 81, 83, 84, 89, 92, 95, 111, 173, 184, 207, 211, 212, 214,218, 221, 223, 224, 225, 226, 227, 232, 233, 240, 241, 242, 243 and 247,C.I. Direct Violets 7, 9, 47, 48, 51, 66, 90, 93, 94, 95, 98, 100 and101, C.I. Acid Reds 35, 42, 52, 57, 62, 80, 82, 111, 114, 118, 119, 127,128, 131, 143, 151, 154, 158, 249, 254, 257, 261, 263, 266, 289, 299,301, 305, 336, 337, 361, 396 and 397, C.I. Acid Violets 5, 34, 43, 47,48, 90, 103 and 126, C.I. Reactive Reds 3, 13, 17, 19, 21, 22, 23, 24,29, 35, 37, 40, 41, 43, 45, 49 and 55, C.I. Reactive Violets 1, 3, 4, 5,6, 7, 8, 9, 16, 17, 22, 23, 24, 26, 27, 33 and 34, C.I. Basic Reds 12,13, 14, 15, 18, 22, 23, 24, 25, 27, 29, 35, 36, 38, 39, 45 and 46, andC.I. Basic Violets 1, 2, 3, 7, 10, 15, 16, 20, 21, 25, 27, 28, 35, 37,39, 40 and 48.

Moreover, in the magenta ink composition of the present invention, thetotal colorant (dye) solid content is preferably 0.6 to 6.0 wt %relative to the total weight of the ink composition. By making the totalcolorant solid content be at least 0.6 wt %, the required colorability(maximum density) can be obtained, and by making the total colorantsolid content be not more than 6.0 wt %, clogging when used in an inkset or the like can be prevented.

In the present invention, to improve the moisture resistance, it ispreferable to use at least one selected from carboxyl group-possessingaromatic compounds and salts thereof. Any aromatic compound having atleast one carboxyl group in the molecular structure thereof or a saltthereof can be used, but the compound preferably has only one carboxylgroup, and moreover preferably has a naphthalene skeleton. Moreover, anaphthalene skeleton-possessing compound having a carboxyl group in the2 position or a salt thereof is more preferable, with an alkali metalsalt of a naphthalene skeleton-possessing compound having a carboxylgroup in the 2 position being yet more preferable. Of alkali metal saltsof a naphthalene skeleton-possessing compound having a carboxyl group inthe 2 position, a lithium salt is preferable in terms of cloggingresistance.

Specific examples of such carboxyl group-possessing aromatic compoundsand salts thereof include 2-hydroxy-1-napthoic acid,1-hydroxy-2-napthoic acid, 1-napthoic acid, 2-napthoic acid,3-hydroxy-2-napthoic acid, 6-hydroxy-2-napthoic acid,3-methoxy-2-napthoic acid, 6-methoxy-2-napthoic acid,6-ethoxy-2-napthoic acid, 6-propoxy-2-napthoic acid, 4-hydroxybenzoicacid, 2,6-naphthalenedicarboxylic acid, and salts thereof (particularlylithium salts).

A salt of a carboxyl group-possessing aromatic compound may be put intothe ink by being added in the form of the salt, or by adding thecarboxyl group-possessing aromatic compound and a base separately.

The content of the at least one selected from such carboxylgroup-possessing aromatic compounds and salts thereof is set inaccordance with the type(s) of the carboxyl group-possessing aromaticcompound(s) and/or salt(s) thereof, the types of the dyes, the types ofsolvent components, and so on, but is preferably in a range of 0.1 to 10wt %, more preferably 0.5 to 5 wt %, relative to the total weight of theink composition.

Moreover, the weight ratio of the total content of the at least oneselected from compounds represented by formula (1) and salts thereof andthe at least one selected from compounds represented by formula (2) andsalts thereof to the total content of the at least one selected fromcarboxyl group-possessing aromatic compounds and salts thereof ispreferably in a range of 5:1 to 1:3, more preferably 3:1 to 1:2. Bymaking this ratio be not more than 5:1, a sufficient moisture resistanceimprovement effect can be obtained, and by making this ratio be at least1:3, good clogging resistance and so on can be easily secured.

To stably dissolve the prescribed colorants and so on, the pH of the inkcomposition (at 20° C.) is preferably at least 8.0. Moreover,considering the material resistance for the various members that willcome into contact with the ink composition, the pH of the inkcomposition is preferably not more than 10.5. To satisfy both of thesethings yet better, the pH of the ink composition is more preferablyadjusted to be within a range of 8.5 to 10.0.

In the magenta ink composition of the present invention, as a mainsolvent, it is preferable to use water or a mixture of water andwater-soluble organic solvents.

As the water, ion exchange water, ultra-filtered water, reverse osmosiswater, distilled water, or the like can be used. Moreover, from theviewpoint of prolonged storage, water that has been subjected to any ofvarious types of chemical sterilization treatment such as addition ofhydrogen peroxide or has been irradiated with ultraviolet rays ispreferable.

In the case of using water as the main solvent in the magenta inkcomposition of the present invention, the content of the water ispreferably 40 to 90 wt %, more preferably 50 to 80 wt %, relative to thetotal weight of the ink composition.

The magenta ink composition of the present invention may further containat least one humectant selected from saccharides and water-solubleorganic solvents having a lower vapor pressure than pure water.

By including a humectant, in ink jet recording, evaporation of water canbe suppressed and hence the ink can be prevented from drying up.Moreover, in the case of a water-soluble organic solvent, the dischargestability can be improved, and the viscosity of the ink can easily bechanged without changing the ink characteristics.

‘Water-soluble organic solvents’ refers to media having the ability todissolve a solute, and are selected from solvents that are organic, arewater-soluble, and have a lower vapor pressure than water. Specifically,polyhydric alcohols such as ethylene glycol, propylene glycol,butanediol, pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol,glycerol, 1,2,6-hexanetriol, diethylene glycol, triethylene glycol anddipropylene glycol, ketones such as acetonyl acetone, esters such asγ-butyrolactone and triethyl phosphate, furfuryl alcohol,tetrahydrofurfuryl alcohol, thiodiglycol, and so on are preferable.

Moreover, as saccharides, maltitol, sorbitol, gluconolactone, maltose,and so on are preferable.

Such humectants are preferably added in a range of 5 to 50 wt %, morepreferably 5 to 30 wt %, yet more preferably 5 to 20 wt %, relative tothe total weight of the ink composition. If the amount added is at least5 wt %, then humectation is obtained, and if the amount added is notmore than 50 wt %, then adjustment to a viscosity enabling use in inkjet recording can be carried out easily.

Moreover, the magenta ink composition of the present inventionpreferably contains a nitrogen-containing organic solvent as a solvent.Examples of such nitrogen-containing organic solvents include1,3-dimethyl-2-imidazolidinone, 2-pyrrolidone, N-methyl-2-pyrrolidone,and c-caprolactam, and of these 2-pyrrolidone is preferably used. Onesuch nitrogen-containing organic solvent may be used alone, or two ormore may be used together.

The content thereof is preferably 0.5 to 10 wt %, more preferably 1 to 5wt %, relative to the total weight of the ink composition. By makingthis content be at least 0.5 wt %, an improvement in the solubility ofthe colorants of the present invention can be achieved, and by makingthis content be not more than 10 wt %, there will be no worsening of thematerial resistance for the various members that will come into contactwith the ink composition.

Moreover, the magenta ink composition of the present inventionpreferably contains a nonionic surfactant, this being as an additiveeffective for obtaining rapid fixing (penetration) of the ink, and alsofor maintaining the circularity of the individual dots.

Examples of nonionic surfactants that can be used in the presentinvention include acetylene glycol type surfactants. Specific examplesof acetylene glycol type surfactants include Surfinol 465 and Surfinol104 (both trade names, made by Air Products and Chemicals Inc.), andOlfine STG and Olfine E1010 (both trade names, made by Nissin ChemicalIndustry Co., Ltd.). The amount added thereof is preferably 0.1 to 5 wt%, more preferably 0.5 to 2 wt %, relative to the total weight of theink composition. By making the amount added be at least 0.1 wt %,sufficient penetrability can be obtained, and by making the amount addedbe not more than 5 wt %, running of images can be easily prevented fromoccurring.

Furthermore, in addition to a nonionic surfactant, by adding a glycolether as a penetration promoter, the penetrability can be furtherincreased, and moreover bleeding at interfaces between adjacent colorinks in the case of carrying out color printing can be reduced, andhence very sharp images can be obtained.

Examples of glycol ethers that can be used in the present inventioninclude ethylene glycol monobutyl ether, diethylene glycol monobutylether, triethylene glycol monoethyl ether, propylene glycol monomethylether, dipropylene glycol monoethyl ether, propylene glycol monobutylether, dipropylene glycol monobutyl ether, and triethylene glycolmonobutyl ether. The amount added thereof is preferably 3 to 30 wt %,more preferably 5 to 15 wt %, relative to the total weight of the inkcomposition. By making the amount added be at least 3 wt %, a sufficientbleeding prevention effect can be obtained, and by making the amountadded be not more than 30 wt %, running of images can be easilyprevented, and good storage stability of the ink can be easily secured.

Furthermore, the ink composition of the present invention may asrequired have added thereto pH regulators such as triethanolamine andalkali metal hydroxides, hydrotropic agents such as urea and derivativesthereof, water-soluble polymers such as sodium alginate, water-solubleresins, fluorinated surfactants, preservatives, fungicides, andcorrosion inhibitors.

Examples of preservatives and fungicides include sodium benzoate, sodiumpentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate,sodium dehydroacetate, and 1,2-dibenzisothiazolin-3-one (Proxel CRL,Proxel BDN, Proxel GXL, Proxel XL-2, and Proxel TN made by Avecia).

Furthermore, examples of pH regulators, dissolution aids andantioxidants include amines such as diethanolamine, triethanolamine,propanolamine and morpholine, and modified compounds thereof, metalhydroxides such as potassium hydroxide, sodium hydroxide and lithiumhydroxide, ammonium salts such as ammonium hydroxide and quaternaryammonium hydroxides (e.g. tetramethylammonium hydroxide), carbonatessuch as potassium carbonate, sodium carbonate and lithium carbonate, andphosphates, and also pyrrolidone compounds such asN-methyl-2-pyrrolidone and 2-pyrrolidone, urea, urea derivatives such asthiourea and tetramethylurea, allophanate compounds such as allophanatesand methylallophanates, biuret compounds such as biuret, dimethylbiuretand tetramethylbiuret, and L-ascorbic acid and salts thereof.

In the ink composition of the present invention, the optional componentsdescribed above may be used alone or a plurality from within the samegroup or from different groups may be selected and used in combination.

Moreover, in the magenta ink composition of the present invention, theamount of all of the components of the ink composition is preferablyselected such that the viscosity of the ink composition is less than 10mPa.s at 20° C.

Moreover, the magenta ink composition of the present inventionpreferably has a surface tension at 20° C. of not more than 45 mN/m,more preferably in a range of 25 to 45 mN/m.

An example of a method of preparing the magenta ink composition of thepresent invention is a method in which the various components arethoroughly mixed together and dissolution is carried out, pressurefiltration is carried out using a membrane filter having a pore size of0.8 μm, and then degassing is carried out using a vacuum pump, thuspreparing the magenta ink composition.

Next, a description will be given of a recording method of the presentinvention using the ink composition described above. As the recordingmethod of the present invention, an ink jet recording method in whichthe ink composition is discharged as drops from fine holes, and thedrops are attached to a recording medium so as to carry out recordingcan be particularly preferably used, but it goes without saying that theink composition can also be used with a general writing instrument, arecorder, a pen plotter, or the like.

As the ink jet recording method, any method that has been publicly knownfrom hitherto can be used, but excellent image recording can be carriedout in particular with a method in which the drops are discharged usingvibration of piezoelectric elements (a recording method using an ink jethead that forms ink drops through mechanical deformation ofelectrostrictive elements) or a method using thermal energy.

EMBODIMENT B

Next, the present invention will be described in detail, showing anotherembodiment thereof (hereinafter referred to as ‘embodiment B’).

An ink composition of the present embodiment contains at least thefollowing in water, or an aqueous medium comprising water andwater-soluble organic solvents: at least one magenta colorant selectedfrom compounds represented by formula (1) (including salts thereof;mention of this will be omitted hereinafter), at least one magentacolorant selected from compounds represented by formula (2) (includingsalts thereof; mention of this will be omitted hereinafter), and atleast one magenta colorant selected from compounds represented byformula (3) (including salts thereof; mention of this will be omittedhereinafter); the ink composition may also be made to contain additivessuch as humectants, viscosity regulators and pH regulators as necessary.

Compounds represented by formula (1) and compounds represented byformula (2) have excellent light-fastness and gas resistance, whereascompounds represented by formula (3) have excellent moisture resistanceand colorability. Consequently, by using these together, it becomespossible to secure all of good light-fastness, gas resistance, moistureresistance, colorability and clogging resistance, and in particular bymaking the contents of the respective compounds be as stated in claim 5,the above properties can be secured with a good balance therebetween.

In the magenta ink composition of embodiment B, as described above, atleast one compound represented by formula (1) and at least one compoundrepresented by formula (2), and in addition at least one compoundrepresented by formula (3) are used as magenta colorants. That is,embodiment B is like embodiment A, except that as an indispensableconstituent feature, at least one magenta colorant selected fromcompounds represented by formula (3) is used as a colorant.Consequently, regarding points other than those described in detailbelow for embodiment B, the matters described earlier for embodiment Aapply similarly to embodiment B.

Compounds represented by formula (3) have an effect of improving thecolorability and moisture resistance. One selected from the group ofcompounds represented by formula (3) may be used alone, or a pluralitymay be used together.

Following are specific examples of compounds represented by formula (3).

The total content of the at least one compound of formula (3) ispreferably in a range of 0.5 to 1.5 wt %, more preferably 0.6 to 1.2 wt%, relative to the total weight of the ink composition. By making thiscontent be at least 0.5 wt %, good colorability can be secured and themoisture resistance can be improved, and by making this content be notmore than 1.5 wt %, a drop in the light-fastness and gas resistance canbe prevented.

In the magenta ink composition of the present invention, the totalcolorant (dye) solid content is preferably 3.5 to 5.5 wt % relative tothe total weight of the ink composition. By making the total colorantsolid content be at least 3.5 wt %, the required colorability (maximumdensity) can be obtained, and by making the total colorant solid contentbe not more than 5.5 wt %, clogging when used in an ink set or the likecan be prevented.

Moreover, the weight ratio of the total content of the at least oneselected from compounds represented by formula (1) and salts thereof,the at least one selected from compounds represented by formula (2) andsalts thereof and the at least one selected from compounds representedby formula (3) and salts thereof to the total content of at least oneselected from carboxyl group-possessing aromatic compounds and saltsthereof is preferably in a range of 5:1 to 1:3, more preferably 3:1 to1:2. By making this ratio be not more than 5:1, a sufficient moistureresistance improvement effect can be obtained, and by making this ratiobe at least 1:3, good clogging resistance and so on can be easilysecured.

EXAMPLES

Following is a more specific description of the present inventionthrough examples and comparative examples. Note, however, that thepresent invention is not limited whatsoever to the materials,compositions and manufacturing methods described in the followingexamples.

Examples A and Comparative Examples A, and Examples B and ComparativeExamples B

Using the mixing proportions shown in Table 7 for ink compositions ofExamples A1 to A15 and Comparative Examples A1 to A4, and the mixingproportions shown in Table 8 for ink compositions of Examples B1 to B9and Comparative Examples B1 to B17, the various components were mixedtogether and dissolution was carried out, and pressure filtration wascarried out using a membrane filter having a pore size of 1 μm, thuspreparing each ink composition. Here, the structure of compound A isthat shown as dye 8 in Table 3 earlier, this being a salt of a compoundrepresented by formula (1). Moreover, the structure of compound B isthat shown in undermentioned formula (7), this being a salt of acompound represented by formula (2). Moreover, the structure of compoundC is that shown as (M-1) earlier, this being a compound represented byformula (3).

Note that the total colorant solid content for each of the Examples andComparative Examples is equal to the total of the colorant componentproportions in Table 7 or 8.

TABLE 7 (EXAMPLES A1 TO A15, COMPARATIVE EXAMPLES A1 TO A4) COMPOUNDCOMPOUND C.I. Direct C.I. Acid 2-NAPHTHOIC A B Red 227 Red 249 ACIDLiOH.H₂O EXAMPLES 1 0.10% 4.00% EXAMPLES 2 2.00% 2.00% EXAMPLES 3 2.70%0.20% EXAMPLES 4 0.80% 5.50% EXAMPLES 5 0.20% 0.20% EXAMPLES 6 1.00%3.00% EXAMPLES 7 1.50% 2.00% EXAMPLES 8 0.50% 1.00% EXAMPLES 9 0.70%0.80% EXAMPLES 10 1.00% 0.50% EXAMPLES 11 2.70% 0.20% 3.00% 0.75%EXAMPLES 12 2.70% 0.20% 3.00% EXAMPLES 13 1.50% 2.00% 3.00% 0.75%EXAMPLES 14 0.70% 0.80% 3.00% 0.75% EXAMPLES 15 1.00% 0.50% 3.00% 0.75%COMPARATIVE EXAMPLES 1 1.20% COMPARATIVE EXAMPLES 2 2.00% COMPARATIVEEXAMPLES 3 3.00% COMPARATIVE EXAMPLES 4 3.00% TRIETHYLENE GLYCOLTRIETHYLENE NaOH GLYCEROL MONOBUTYL ETHER GLYCOL 2-PYRROLIDONE EXAMPLES1 10.0% 10.0% 1.9% 2.5% EXAMPLES 2 10.0% 10.0% 2.0% 2.5% EXAMPLES 310.0% 10.0% 3.1% 2.5% EXAMPLES 4 10.0% 10.0% 2.2% EXAMPLES 5 10.0% 10.0%5.6% 2.5% EXAMPLES 6 0.70% 10.0% 10.0% 1.3% 2.5% EXAMPLES 7 10.0% 10.0%2.5% 2.5% EXAMPLES 8 10.0% 10.0% 4.8% 2.2% EXAMPLES 9 10.0% 10.0% 4.5%2.5% EXAMPLES 10 10.0% 10.0% 4.5% 2.5% EXAMPLES 11 10.0% 10.0% 1.8%EXAMPLES 12 0.70% 10.0% 10.0% 0.7% 1.5% EXAMPLES 13 10.0% 10.0% 1.2%EXAMPLES 14 10.0% 10.0% 0.7% 2.5% EXAMPLES 15 10.0% 10.0% 0.7% 2.5%COMPARATIVE EXAMPLES 1 10.0% 10.0% 4.8% 2.5% COMPARATIVE EXAMPLES 210.0% 10.0% 4.0% 2.5% COMPARATIVE EXAMPLES 3 10.0% 10.0% 3.0% 2.5%COMPARATIVE EXAMPLES 4 10.0% 10.0% 3.0% 2.5% OLFINE PROXEL ULTRAPURETRIETHANOLAMINE E1010(*1) XL-2(*2) WATER TOTAL EXAMPLES 1 0.6% 0.8% 0.3%69.80% 100% EXAMPLES 2 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 3 0.6% 0.8%0.3% 69.80% 100% EXAMPLES 4 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 5 0.6%0.8% 0.3% 69.80% 100% EXAMPLES 6 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 70.6% 0.8% 0.3% 69.80% 100% EXAMPLES 8 0.6% 0.8% 0.3% 69.80% 100%EXAMPLES 9 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 10 0.6% 0.8% 0.3% 69.80%100% EXAMPLES 11 0.6% 0.8% 0.3% 69.85% 100% EXAMPLES 12 0.6% 0.8% 0.3%69.50% 100% EXAMPLES 13 0.6% 0.8% 0.3% 69.85% 100% EXAMPLES 14 0.6% 0.8%0.3% 69.85% 100% EXAMPLES 15 0.6% 0.8% 0.3% 69.85% 100% COMPARATIVEEXAMPLES 1 0.6% 0.8% 0.3% 69.80% 100% COMPARATIVE EXAMPLES 2 0.6% 0.8%0.3% 69.80% 100% COMPARATIVE EXAMPLES 3 0.6% 0.8% 0.3% 69.80% 100%COMPARATIVE EXAMPLES 4 0.6% 0.8% 0.3% 69.80% 100%PERCENTAGES IN THE TABLE ARE WT %(*1)MADE BY NISSIN CHEMINAL INDUSTRY CO., LTD(*2)MADE BY AVECIA

TABLE 8 (EXAMPLES B1 TO B9, COMPARATIVE EXAMPLES B1 TO B17) COMPOUNDCOMPOUND COMPOUND C.I. Direct C.I. Acid 2-NAPHTHOIC GLY- A B C Red 227Red 249 ACID LiOH.H₂O NaOH CEROL EXAMPLES 1 0.50% 1.50% 1.00% 10.0%EXAMPLES 2 0.50% 5.50% 1.00% 10.0% EXAMPLES 3 2.00% 3.00% 1.00% 10.0%EXAMPLES 4 0.20% 3.00% 1.00% 10.0% EXAMPLES 5 0.50% 3.00% 0.30% 10.0%EXAMPLES 6 0.50% 3.00% 2.00% 10.0% EXAMPLES 7 0.50% 3.00% 1.00% 10.0%EXAMPLES 8 0.50% 3.00% 1.00% 3.00% 0.70% 10.0% EXAMPLES 9 0.50% 3.00%1.00% 3.00% 0.75% 10.0% COMPARATIVE 3.50% 10.0% EXAMPLES 1 COMPARATIVE3.50% 3.00% 0.75% 10.0% EXAMPLES 2 COMPARATIVE 4.50% 10.0% EXAMPLES 3COMPARATIVE 4.50% 3.00% 0.75% 10.0% EXAMPLES 4 COMPARATIVE 3.00% 10.0%EXAMPLES 5 COMPARATIVE 3.00% 10.0% EXAMPLES 6 COMPARATIVE 3.00% 10.0%EXAMPLES 7 COMPARATIVE 3.00% 3.00% 0.75% 10.0% EXAMPLES 8 COMPARATIVE1.00% 4.00% 10.0% EXAMPLES 9 COMPARATIVE 1.00% 4.00% 3.00% 0.75% 10.0%EXAMPLES 10 COMPARATIVE 1.20% 1.20% 10.0% EXAMPLES 11 COMPARATIVE 1.20%1.20% 3.00% 0.75% 10.0% EXAMPLES 12 COMPARATIVE 3.00% 1.00% 10.0%EXAMPLES 13 COMPARATIVE 0.50% 3.00% 1.00% 10.0% EXAMPLES 14 COMPARATIVE0.50% 3.00% 1.00% 3.00% 0.75% 10.0% EXAMPLES 15 COMPARATIVE 0.50% 3.00%0.50% 10.0% EXAMPLES 16 COMPARATIVE 0.50% 3.00% 0.50% 3.00% 0.75% 10.0%EXAMPLES 17 TRIETHYLENE GLYCOL TRIETHYLENE 2-PYRRO- TRIETHA- OLFINEPROXEL ULTRAPURE MONOBUTYL ETHER GLYCOL LIDONE NOLAMINE E1010(*1)XL-2(*2) WATER TOTAL EXAMPLES 1 10.0% 3.0% 2.5% 0.6% 0.8% 0.3% 69.80%100% EXAMPLES 2 10.0% 1.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 3 10.0%2.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 4 10.0% 2.0% 2.5% 0.6% 0.8%0.3% 69.80% 100% EXAMPLES 5 10.0% 2.0% 2.5% 0.6% 0.8% 0.3% 69.50% 100%EXAMPLES 6 10.0% 2.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 7 10.0% 1.0%2.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 8 10.0% 0.5% 0.6% 0.8% 0.3%69.80% 100% EXAMPLES 9 10.0% 0.5% 0.6% 0.8% 0.3% 69.80% 100% COMPARATIVE10.0% 2.0% 2.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 1 COMPARATIVE 10.0%1.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 2 COMPARATIVE 10.0% 1.0% 2.5%0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 3 COMPARATIVE 10.0% 0.5% 0.6% 0.8%0.3% 69.80% 100% EXAMPLES 4 COMPARATIVE 10.0% 3.0% 2.5% 0.6% 0.8% 0.3%69.80% 100% EXAMPLES 5 COMPARATIVE 10.0% 3.0% 2.5% 0.6% 0.8% 0.3% 69.80%100% EXAMPLES 6 COMPARATIVE 10.0% 3.0% 2.5% 0.6% 0.8% 0.3% 69.80% 100%EXAMPLES 7 COMPARATIVE 10.0% 1.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 8COMPARATIVE 10.0% 1.0% 2.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 9COMPARATIVE 10.0% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 10 COMPARATIVE10.0% 4.0% 2.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 11 COMPARATIVE 10.0%2.5% 0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 12 COMPARATIVE 10.0% 2.0% 2.5%0.6% 0.8% 0.3% 69.80% 100% EXAMPLES 13 COMPARATIVE 10.0% 1.0% 2.5% 0.6%0.8% 0.3% 69.80% 100% EXAMPLES 14 COMPARATIVE 10.0% 0.5% 0.6% 0.8% 0.3%69.80% 100% EXAMPLES 15 COMPARATIVE 10.0% 2.0% 2.5% 0.6% 0.8% 0.3%69.80% 100% EXAMPLES 16 COMPARATIVE 10.0% 0.5% 0.6% 0.8% 0.3% 69.80%100% EXAMPLES 17PERCENTAGES IN THE TABLE ARE WT %(*1)MADE BY NISSIN CHEMINAL INDUSTRY CO., LTD(*2)MADE BY AVECIA

Using an EM930C ink jet printer (made by Seiko Epson Corporation), eachof the above ink compositions was filled into a cartridge (magentachamber) specially for this ink jet printer, and printing was carriedout onto a recording medium specially for ink jet recording (PMphotographic paper made by Seiko Epson Corporation), and variousevaluations were carried out. The results obtained are shown in Tables 9and 10 (Examples A and Comparative Examples A) and Table 11 (Examples Band Comparative Examples B).

<Light-fastness Test>

Using a cartridge filled with the ink composition of each of theExamples and Comparative Examples, printing was carried out with theprint duty adjusted such that the OD (optical density) was in a range of0.9 to 1.1, and the printed article obtained was exposed for 11 daysunder conditions of 24° C., a relative humidity (RH) of 60%, and anillumination of 70,000 lux using an STF-II (trade name, made by SugaTest Instruments Co., Ltd.) fluorescent lamp weathering resistancetester.

After the exposure, the optical density of each printed article wasmeasured using a reflection densitometer (‘Spectrolino’ (trade name)made by Gretag), the relict optical density (ROD) was determined usingthe following equation, and evaluation was carried out using thefollowing judgement criteria.ROD(%)=(D/D ₀)×100

-   -   D: OD after exposure test    -   D₀: OD before exposure test

(Measurement conditions: Filter: red, light source: D50, visual fieldangle: 2°)

[Judgement Criteria for Examples A and Comparative Examples A]

-   -   Evaluation 1: ROD at least 90%    -   Evaluation 2: ROD at least 80% but less than 90%    -   Evaluation 3: ROD at least 70% but less than 80%    -   Evaluation 4: ROD at least 60% but less than 70%    -   Evaluation 5: ROD less than 60%

[Judgement criteria for Examples B and Comparative Examples B]

-   -   Evaluation 1: ROD at least 85%    -   Evaluation 2: ROD at least 70% but less than 85%    -   Evaluation 3: ROD at least 55% but less than 70%    -   Evaluation 4: ROD less than 55%        <Evaluation of Gas Resistance (Ozone Resistance)>

Using a cartridge filled with the ink composition of each of theExamples and Comparative Examples, printing was carried out with theprint duty adjusted such that the OD (optical density) was in a range of0.9 to 1.1, and the printed article obtained was exposed for 24 hoursunder conditions of 24° C., a relative humidity (RH) of 60%, and anozone concentration of 10 ppm using an OMS—H (trade name, made by SugaTest Instruments Co., Ltd.) ozone weather meter.

After the exposure, the optical density of each printed article wasmeasured using a reflection densitometer (‘Spectrolino’ (trade name)made by Gretag), the relict optical density (ROD) was determined usingthe following equation, and evaluation was carried out using thefollowing judgement criteria.ROD(%)=(D/D ₀)×100

-   -   D: OD after exposure test    -   D₀: OD before exposure test

(Measurement conditions: Filter: red, light source: D50, visual fieldangle: 2°)

[Judgement criteria for Examples A and Comparative Examples A]

-   -   Evaluation 1: ROD at least 90%    -   Evaluation 2: ROD at least 80% but less than 90%    -   Evaluation 3: ROD at least 70% but less than 80%    -   Evaluation 4: ROD at least 60% but less than 70%    -   Evaluation 5: ROD less than 60%

[Judgement criteria for Examples B and Comparative Examples B]

-   -   Evaluation 1: ROD at least 85%    -   Evaluation 2: ROD at least 70% but less than 85%    -   Evaluation 3: ROD at least 55% but less than 70%    -   Evaluation 4: ROD less than 55%        <Evaluation of Moisture Resistance>

Using a cartridge filled with the ink composition of each of theExamples and Comparative Examples, characters and reverse characterswere printed under discharge conditions such that the firing amount was1.5 to 2.2 mg per square inch. The printed article obtained was driedfor 24 hours at 25° C. and 40% RH, and was then left at 40° C. and 85%RH for 3 days for the ink compositions of Examples A or 7 days for theink compositions of Examples B and Comparative Examples B; running ofthe dyes (or collapsing of the reverse characters) was observedvisually, and evaluation was carried out using the following judgementcriteria.

[Judgement criteria]

-   -   Evaluation 1: Running of dyes hardly observed at all.    -   Evaluation 2: Some running of dyes, outline of characters        slightly broken up    -   Evaluation 3: Running of dyes observed, outline of characters        broken up    -   Evaluation 4: Running of dyes observed, characters thickened,        reverse characters filled in    -   Evaluation 5: Marked running of dyes observed, characters and        reverse characters unreadable        <Evaluation of Clogging Resistance>

Using a cartridge filled with the ink composition of each of theExamples and Comparative Examples, printing was carried out continuouslyfor 10 minutes, and once it had been confirmed that all of the nozzleswere discharging normally, the system was left for 21 days at 60° C. and15% RH. After this, a cleaning operation was repeated until the nozzlesdischarged on a par with initially, and evaluation was carried out usingthe following judgement criteria.

[Judgement criteria]

-   -   Evaluation 1: Returns to on a par with initially as soon as the        power is turned on or after carrying out the cleaning operation        1 to 4 times    -   Evaluation 2: Returns to on a par with initially after carrying        out the cleaning operation 5 to 8 times    -   Evaluation 3: Returns to on a par with initially after carrying        out the cleaning operation 9 to 12 times    -   Evaluation 4: Doesn't return to on a par with initially even        after carrying out the cleaning operation 13 times        <Evaluation of Maximum Density>

Using a cartridge filled with the ink composition of each of Examples Band Comparative Examples B, for each ink composition printing wascarried out with the print duty adjusted to maximum. The OD of eachsample was then measured using a reflection densitometer (‘Spectrolino’(trade name) made by Gretag), and evaluation was carried out using thefollowing judgement criteria.

[Judgement criteria]

-   -   Evaluation 1: OD at least 2.2    -   Evaluation 2: OD at least 2.1 but less than 2.2    -   Evaluation 3: OD at least 2.0 but less than 2.1    -   Evaluation 4: OD less than 2.0        <Evaluation of Overall Performance>

For Examples B and Comparative Examples B, the total of the evaluationresults for the various items is shown as the overall performance (thelower the value, the better the overall performance). TABLE 9 (EXAMPLESA1 TO A10, COMPARATIVE EXAMPLES A1 TO A4) LIGHT- GAS FASTNESS RESISTANCEEXAMPLES 1 2 1 EXAMPLES 2 1 1 EXAMPLES 3 1 2 EXAMPLES 4 2 1 EXAMPLES 5 11 EXAMPLES 6 1 1 EXAMPLES 7 1 1 EXAMPLES 8 1 1 EXAMPLES 9 1 1 EXAMPLES10 1 1 COMPARATIVE EXAMPLES 1 1 3 COMPARATIVE EXAMPLES 2 3 1 COMPARATIVEEXAMPLES 3 5 5 COMPARATIVE EXAMPLES 4 5 5

TABLE 10 (EXAMPLES A1 TO A15) MOISTURE CLOGGING RESISTANCE RESISTANCEEXAMPLES 1 2 1 EXAMPLES 2 3 1 EXAMPLES 3 4 1 EXAMPLES 4 3 2 EXAMPLES 5 21 EXAMPLES 6 3 1 EXAMPLES 7 3 1 EXAMPLES 8 2 1 EXAMPLES 9 2 1 EXAMPLES10 2 1 EXAMPLES 11 2 1 EXAMPLES 12 2 2 EXAMPLES 13 2 1 EXAMPLES 14 1 1EXAMPLES 15 1 1

TABLE 11 (EXAMPLES B1 TO B9 AND COMPARATIVE EXAMPLES B1 TO B17) LIGHT-GAS MOISTURE CLOGGING MAXIMUM OVERALL FASTNESS RESISTANCE RESISTANCERESISTANCE DENSITY PERFORMANCE EXAMPLES 1 2 2 2 1 2 9 EXAMPLES 2 2 1 3 31 10 EXAMPLES 3 1 2 3 2 1 9 EXAMPLES 4 2 2 2 2 2 10 EXAMPLES 5 1 1 3 1 39 EXAMPLES 6 2 2 2 2 1 9 EXAMPLES 7 1 1 3 2 1 8 EXAMPLES 8 1 1 2 3 1 8EXAMPLES 9 1 1 2 2 1 7 COMPARATIVE EXAMPLES 1 1 2 5 1 3 12 COMPARATIVEEXAMPLES 2 1 2 5 1 3 12 COMPARATIVE EXAMPLES 3 2 1 4 2 4 13 COMPARATIVEEXAMPLES 4 2 1 3 2 4 12 COMPARATIVE EXAMPLES 5 4 4 1 1 1 11 COMPARATIVEEXAMPLES 6 4 4 1 2 1 12 COMPARATIVE EXAMPLES 7 4 4 5 2 1 16 COMPARATIVEEXAMPLES 8 4 4 5 2 1 16 COMPARATIVE EXAMPLES 9 1 1 5 2 3 12 COMPARATIVEEXAMPLES 10 1 1 4 2 3 11 COMPARATIVE EXAMPLES 11 3 3 4 1 2 13COMPARATIVE EXAMPLES 12 3 3 3 1 2 12 COMPARATIVE EXAMPLES 13 3 3 2 2 212 COMPARATIVE EXAMPLES 14 3 3 3 2 1 12 COMPARATIVE EXAMPLES 15 3 3 2 21 11 COMPARATIVE EXAMPLES 16 3 3 5 2 1 14 COMPARATIVE EXAMPLES 17 3 3 52 1 14

The following are clear from the results in Tables 9 and 10.

For Comparative Examples A1 and A2 in which the compound of formula (1)or the compound of formula (2) was used alone, the light-fastness andthe gas resistance were better than for Comparative Examples A3 and A4in which a conventional dye was used, but yet better light-fastness andgas resistance were exhibited for Examples A1 to A10 in which thecompound of formula (1) and the compound of formula (2) were usedtogether. For Examples A2 and A6 to A10 in which the contents of thecompound of formula (1) and the compound of formula (2) and the ratiotherebetween were made to be within preferable ranges, thelight-fastness and gas resistance were further improved. Moreover, forExamples A11 to A15 in which an aromatic carboxylic acid (2-napthoicacid) was used, the moisture resistance was further improved. Theclogging resistance was good for all of Examples A.

Moreover, the following are clear from the results in Table 11.

Compared with the Comparative Examples in which compound A, B or C wasused alone as a colorant or two thereof were used together (ComparativeExamples B1, B3, B5, B9, B11, B13), the overall performance was betterfor the Examples in which all three were used together (Examples B1 toB7). Moreover, compared with the Comparative Examples in which threedyes were used together including a dye other than compounds of formulae(1) to (3) (Comparative Examples B14, B16), the overall performance wasbetter for the Examples (Examples B1 to B7). For the Example in whichthe contents of all of the compounds A, B and C were within preferableranges (Example B7), the overall performance was particularly good.

Moreover, for the Examples in which a carboxyl group-possessing aromaticcompound (2-napthoic acid) was used (Examples B8, B9), an improvement inthe moisture resistance was further seen.

1. A magenta ink composition, containing, as colorants, at least oneselected from compounds represented by undermentioned formula (1) andsalts thereof, and at least one selected from compounds represented byundermentioned formula (2) and salts thereof.

(In formula (1), A represents a residue of a 5-membered heterocyclicdiazo component A-NH₂; B¹ and B² represent —CR¹═ and —CR²═ respectively,or one thereof represents a nitrogen atom and the other thereofrepresents —CR¹═ or —CR²═; R⁵ and R⁶ each independently represents ahydrogen atom, an aliphatic group, an aromatic group, a heterocyclicgroup, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group,a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or asulfamoyl group, each group being optionally substituted; G, R¹ and R²each independently represents a hydrogen atom, a halogen atom, analiphatic group, an aromatic group, a heterocyclic group, a cyano group,a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, anaryloxycarbonyl group, an acyl group, a hydroxy group, an alkoxy group,an aryloxy group, a silyloxy group, an acyloxy group, a carbamoyloxygroup, a heterocyclic oxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an alkyl group-, aryl group-, or heterocyclicgroup-substituted amino group, an acylamino group, a ureido group, asulfamoylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, an alkyl- or aryl-sulfonylamino group, anitro group, an alkyl- or aryl-thio group, an alkyl- or aryl-sulfonylgroup, an alkyl- or aryl-sulfinyl group, a sulfamoyl group, a sulfogroup, or a heterocyclic thio group, each group being optionallysubstituted; and R¹ and R⁵, or R⁵ and R⁶ may be bonded together to forma 5- or 6-membered ring.)

(In formula (2), A represents an alkylene group, a phenylenegroup-containing alkylene group, or

(wherein R represents a hydrogen atom or an alkyl group), and Xrepresents NH₂, OH or Cl.)
 2. The magenta ink composition according toclaim 1, containing, as colorants, at least one selected from saidcompounds represented by formula (1) and salts thereof, at least oneselected from said compounds represented by formula (2) and saltsthereof, and at least one selected from compounds represented by undermentioned formula (3).

[In formula (3), Y represents a phenyl group or naphthyl groupsubstituted with a C₁ to C₄ alkyl group or alkoxy group, OH, SO₃H orCOOM; B represents H, or the following formula

(here, R²¹ represents H or a C₁ to C₄ alkyl group substituted with OH orCOOH, R²² represents a C₁ to C₄ alkyl group or phenyl group substitutedwith OH, OCH₃, OC₂H₅, SO₃M, or COOM, R²³ represents OH, COOH, or NHR²⁴,and R²⁴ represents a C₁ to C₄ alkyl group substituted with SO₃M orCOOH); and M represents H, Li, Na, K, ammonium, or an organic amine. 3.The magenta ink composition according to claim 1, wherein said compoundsrepresented by formula (1) and salts thereof are compounds representedby undermentioned formula (4) and salts thereof

(In Formula (4), Z¹ represents an electron-withdrawing group having aHammett substituent constant p value of at least 0.20; Z² represents ahydrogen atom, an aliphatic group, an aromatic group, or a heterocyclicgroup, R¹, R², R⁵ and R⁶ are defined as in the case of formula (1), R³and R⁴ each independently represents a hydrogen atom, an aliphaticgroup, an aromatic group, a heterocyclic group, an acyl group, analkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, asulfonyl group, or a sulfamoyl group; Q represents a hydrogen atom, analiphatic group, an aromatic group, or a heterocyclic group, and each ofZ¹, Z², R¹ to R⁶, and Q may be further substituted.)
 4. The magenta inkcomposition according to claim 1, containing 0.2 to 2.5 wt % in total ofthe at least one selected from said compounds represented by formula (1)and salts thereof, and 0.4 to 5.0 wt % in total of the at least oneselected from said compounds represented by formula (2) and saltsthereof, relative to the total weight of the ink composition.
 5. Themagenta ink composition according to claim 2, containing 0.3 to 1.5 wt %in total of the at least one selected from said compounds represented byformula (1) and salts thereof, 2.0 to 5.0 wt % in total of the at leastone selected from said compounds represented by formula (2) and saltsthereof, and 0.5 to 1.5 wt % in total of the at least one selected fromsaid compounds represented by formula (3), relative to the total weightof the ink composition.
 6. The magenta ink composition according toclaim 1, having a total colorant solid content of 0.6 to 6.0 wt %relative to the total weight of the ink composition.
 7. The magenta inkcomposition according to claim 2, having a total colorant solid contentof 3.5 to 5.5 wt % relative to the total weight of the ink composition.8. The magenta ink composition according to claim 1, wherein the weightratio of the total content of the at least one selected from saidcompounds represented by formula (1) and salts thereof to the totalcontent of the at least one selected from said compounds represented byformula (2) and salts thereof is in a range of 3:1 to 1:5.
 9. Themagenta ink composition according to claim 1, further containing atleast one selected from carboxyl group-possessing aromatic compounds andsalts thereof.
 10. The magenta ink composition according to claim 2,further containing at least one selected from carboxyl group-possessingaromatic compounds and salts thereof.
 11. The magenta ink compositionaccording to claim 9, wherein said carboxyl group-possessing aromaticcompounds and salts thereof are aromatic compounds having one carboxylgroup and salts thereof
 12. The magenta ink composition according toclaim 9, wherein said carboxyl group-possessing aromatic compounds andsalts thereof are naphthalene skeleton-possessing compounds and saltsthereof
 13. The magenta ink composition according to claim 12, whereinsaid naphthalene skeleton-possessing compounds and salts thereof arecompounds having a carboxyl group in the 2 position and salts thereof14. The magenta ink composition according to claim 13, wherein saidnaphthalene skeleton-possessing compounds having a carboxyl group in the2 position and salts thereof are 2-napthoic acid, 3-hydroxy-2-napthoicacid, 6-hydroxy-2-napthoic acid, 6-methoxy-2-napthoic acid, and saltsthereof.
 15. The magenta ink composition according to claim 9, whereinthe salts of said carboxyl group-possessing aromatic compounds arelithium salts.
 16. The magenta ink composition according to claim 9,wherein the weight ratio of the total content of the at least oneselected from said compounds represented by formula (1) and saltsthereof and the at least one selected from said compounds represented byformula (2) and salts thereof to the total content of the at least oneselected from said carboxyl group-possessing aromatic compounds andsalts thereof is in a range of 5:1 to 1:3.
 17. The magenta inkcomposition according to claim 10, wherein the weight ratio of the totalcontent of the at least one selected from said compounds represented byformula (1) and salts thereof, the at least one selected from saidcompounds represented by formula (2) and salts thereof and the at leastone selected from said compounds represented by formula (3) and saltsthereof to the total content of the at least one selected from saidcarboxyl group-possessing aromatic compounds and salts thereof is in arange of 5:1 to 1:3.
 18. The magenta ink composition according to claim1, wherein the magenta ink composition is used in an ink jet recordingmethod.
 19. The magenta ink composition according to claim 18, whereinsaid ink jet recording method is a recording method using an ink jethead that forms ink drops through mechanical deformation ofelectrostrictive elements.
 20. An ink jet recording method, comprisingcarrying out recording by discharging drops of an ink composition andattaching the drops to a recording medium, wherein the ink jet recordingmethod uses the magenta ink composition according to claim 1 as the inkcomposition.
 21. A recorded article, obtained by recording using therecording method according to claim 20.